The Egyptian capital Cairo is poised for renewed protests as supporters of ousted President Mohammed Morsi call for marches after Friday prayers.
It comes two days after authorities broke up Muslim Brotherhood protest camps in the Egyptian capital with the loss of at least 638 lives.
Egypt is in a state of emergency and police have been authorised to use live ammunition in self-defence.
Meanwhile, Egypt’s interim leaders have criticised remarks by President Obama.
On Thursday, Mr Obama condemned the government’s actions in ordering security forces to break up the protest camps, and cancelled joint military exercises.
He said co-operation could not continue while civilians were being killed. However, he stopped short of cutting $1.3bn (£830m) in aid that the US gives to Egypt.
The Egyptian presidency said in a statement on Friday that Mr Obama’s words were “not based on fact” and would “embolden armed groups”.
It said Egypt was facing “terrorist acts”.
The Muslim Brotherhood called on its supporters to gather in mosques for Friday prayers and then take to the streets of Cairo.
The group’s leaders say they will hold marches under the slogan “the people want to topple the coup”.
In response, a pro-government group has called on people to protect their neighbourhoods and churches throughout the country.
Egypt’s Coptic Christian community has been targeted by some Islamists who accuse the Church of backing the army’s overthrow of President Morsi last month.
There are fears of renewed bloodshed after authorities said the police were authorised to use live ammunition to protect themselves and key state institutions from attack.
The BBC’s Bethany Bell in Cairo says Egyptians will be watching to see if the Brotherhood will gain some fresh momentum after the crackdown on Wednesday – or if the army will strengthen its grip on power.
Reports say there were renewed attacks on security forces on Thursday, with at least seven soldiers and a policeman killed in the Sinai peninsula and another police officer killed in the central city of Assuit.
US Republican Senator John McCain told BBC Newsnight that the ousting of President Morsi was a “coup” and President Obama should have cut off aid to Egypt as a result.
The US has been careful not to used the word coup as under US law this would mean stopping aid.
“I am confused that we would not enforce our own laws,” he said.
“That sends a message of tolerance of brutality, of ineffective American leadership to the Muslim world, that the United States of America at least condones this kind of behaviour, which we cannot.”
‘Maximum restraint’
Wednesday’s bloodshed has drawn widespread international condemnation.
Late on Thursday, the UN Security Council met in emergency session at the request of France, Britain and Australia.
Following the meeting, Argentina’s ambassador to the UN, Maria Cristina Perceval, said the Council called for the Egyptian government and the Muslim Brotherhood to exercise “maximum restraint” and to end the violence.
Turkey, which described Wednesday’s events as a “massacre”, has recalled its ambassador to Cairo “to discuss the latest developments”.
Wednesday’s violence began when armoured bulldozers moved into the two Cairo protest camps.
The smaller of the two camps, at Nahda Square, was cleared quickly but clashes raged for several hours in and around the main encampment near the Rabaa al-Adawiya mosque. The mosque was badly damaged by fire.
Egyptian interim Prime Minister Hazem Beblawi said the authorities had to restore security.
Mr Morsi, Egypt’s first democratically elected president, is in custody charged with murder over a 2011 jailbreak. His period of detention was extended by 30 days on Thursday, state media said.